On success, the X-Success HTTP header has the value 1 while in case of failure it has the value 0. On success, the HTTP status code will be the standard 200 OK. On error, an error message is present in the X-Error-Message HTTP header. In case of failure, the following HTTP status codes are returned :
401 - Unauthorized
This means that the authentication token is invalid. You will have to authenticate before calling the operation.
404 - Not Found
In case something (e.g. table) is not found.
400 - Bad Request
There is some other error.
403 - Forbidden
Either the function call you are making is not allowed or you have exceeded the rate limit.
In addition, the following headers are present that can help in further debugging :
X-Last-SQL
The last SQL statement executed.
X-Error-Exception
The name of the error class e.g. SQLException, NotFoundException, etc.